Lethargy is a state of drowsiness, inactivity, or indifference in which there are delayed responses to external stimuli such as auditory (sound), visual (sight), or tactile (touch) stimuli. Lethargy may also refer to the general malaise and decreased activity exhibited by cats that do not feel well.
Lethargy is a nonspecific sign associated with many possible underlying systemic disorders. It may have little to no impact on the affected individual; however its presence may represent severe or life-threatening illness. Lethargy of more than a day's duration should not be ignored, and should be addressed, especially if it persists.
General Causes of Lethargy in Cats
Anemia (low red blood cell count)
Other blood disorders
Cardiovascular (heart and vessels) and pulmonary (respiratory) disorders
Chronic inflammation or infection
Drug or medication related
Electrolyte abnormalities
Endocrine (hormonal) or metabolic disorders
Gastrointestinal diseases
Urinary tract disorders
Cancer
Immune diseases
Certain severe skin diseases
Certain eye diseases, particularly those associated with blindness
Neurologic and neuromuscular disorders
Nutritional disorders
Behavioral disorders
Skeletal diseases
Infectious diseases
Exposure to certain toxins
Physical trauma
What to Watch For
A general change in demeanor
Listlessness
Reluctance to play, exercise or perform normal behaviors
Hiding, avoiding contact with people or other pets
As lethargy is a very nonspecific sign and is associated with dozens of physical ailments in cats, baseline laboratory tests are useful in identifying any systemic abnormalities that should be pursued with further testing. Examples of these baseline screening tests include:
Complete blood count (CBC)
Biochemical profile
Urinalysis
Fecal examination
Chest and abdominal radiographs (X-rays)
If baseline tests are inconclusive or if abnormalities are detected, your veterinarian may consider doing additional diagnostic tests in your cat, such as:
Abdominal or thoracic/cardiac ultrasound
Serologic testing for infectious diseases
Bacterial culture of the urine, feces or blood
Endocrine (hormone) assays
X-rays of various parts of the skeleton
Cytology and biopsy of abnormal fluid or tissues
Complete eye examination
Complete neurologic examination
Complete behavioral assessment
Certain immunologic tests
Computed Tomography (CT scan)
Magnetic resonance imaging (MRI)
Treatment of Feline Lethargy
When the underlying problem is unknown, it may be difficult or even impossible to treat lethargy symptomatically. Identifying an underlying cause is essential in determining the appropriate treatment plan and care of the patient.
Home Care
Once therapy has been instituted administer any prescribed medications as directed by your veterinarian. Observe your cat's general activity and appetite, and notify your veterinarian if any of the symptoms worsen or change.
Lethargy should not be ignored; it is a nonspecific sign associated with multiple possible underlying disorders.
